Review of Skidding Problems at Navy Airfields 1 Review of Work Conducted on Friction Coefficient 2

A review of the problem of aircraft skidding on Naval airfields during landings and a thorough literature search on the work conducted on friction coefficient were made. The literature search revealed that much ,vork has been conducted on basic theoretical studies of friction coefficient, on development of friction measuring devices, and on investigations to determine the factors which affect the friction coefficient between tires and pavement surfaces. It was found that low friction coefficients were responsible for some aircraft accidents on Naval airfields. Basic studies indicated that the actual friction coefficients between tires and pavement surfaces did not follow the basic laws of friction. The total frlctional force included, in addition to the basic frictional force, a mechanical force resulting from the interlocking of the rubber with the aggregate particles protruding above the pavement surfaces. Various field-testing devices have been developed by others, used, and compared in an effort to locate low-friction pavements and to standardize the method of measurement. One device still in the development stage showed promise of measuring friction coefficient under simulated conditions of landing aircraft. Many factors affecting the friction coefficient between tires and pavement surfaces have been found through laboratory and field investigations. These factors were related to vehicle and aircraft operation, to tire design, and to types of pavement surfaces. The effect of these factors on the friction coefficients were varied. The individual effects of each factor were not found sinco many of the factors worked in combination. The review of the problem and of the work conducted on friction coefficient is summarized. A recommendation is given to the effect that no effort be made at this time to develop a friction measuring device. Copi*« avoilobll Th« Laboratory invites comment on"nil*«t.f »il, particularly on th« rosulta obtained by that« who havo appliad tha information.